股指期货合约有确定的到期日，不能无限期持有。 ( )
参考答案：对
查密度表，比较体积相同的酒精和汽油，质量较大的是______；比较质量相同的铅块和铁块，体积较大的是______．
.
— Do you know why the teacher asks for me?
— He wants you to _________ your absence(缺席) last night.
A．account for
B．call for
C．reach for
D．send for
